An artists' collective has taken credit for exposing US Republican presidential candidate Donald Trump to unflattering scrutiny, saying it is responsible for life-sized nude statues of the tycoon.

Naked statues of Mr Trump featuring a massive belly, small fingers and missing genital parts appeared in Manhattan, New York and four other US cities on Thursday morning as part of a project by anarchist collective Indecline titled 'The Emperor Has No Balls'.

The collective said Mr Trump represents "our modern-day emperor of fascism and bigotry". A video posted to the collective's website shows the process involved in making the clay statues.

Bemused onlookers immediately gathered around the statues to pose for photos and video. While police in New York city were quick to remove the statue from Union Square, copies in the west coast cities of San Francisco, Los Angeles and Seattle were still there nine hours later, The Daily Beast reported.

Trump supporters were quick to cry foul, saying similar statues of presidential rival Hillary Clinton would never have appeared. 

But an Indecline spokesman suggested otherwise. 

"Hillary’s not much better than Trump so we’ll probably make one of her too," he said.